In Vivo Bone Effects of a Novel Bisphosphonate-EP4a Conjugate Drug (C3) for Reversing Osteoporotic Bone Loss in an Ovariectomized Rat Model.

Pathological bone loss is a regular feature of postmenopausal osteoporosis, and the microstructural changes along with the bone loss make the individual prone to getting hip, spine, and wrist fractures. We have developed a new conjugate drug named C3, which has a synthetic, stable EP4 agonist (EP4a) covalently linked to an inactive alendronate (ALN) that binds to bone and allows physiological remodeling. After losing bone for 12 weeks, seven groups of rats were treated for 8 weeks via tail-vein injection. The groups were: C3 conjugate at low and high doses, vehicle-treated ovariectomy (OVX) and sham, C1 (a similar conjugate, but with active ALN at high dose), inactive ALN alone, and a mixture of unconjugated ALN and EP4a to evaluate the conjugation effects. Bone turnover was determined by dynamic and static histomorphometry; µCT was employed to determine bone microarchitecture; and bone mechanical properties were evaluated via biomechanical testing. Treatment with C3 significantly increased trabecular bone volume and vertebral BMD versus OVX controls. There was also significant improvement in the vertebral load-bearing abilities and stimulation of bone formation in femurs after C3 treatment. This preclinical research revealed that C3 resulted in significant anabolic effects on trabecular bone, and EP4a and ALN conjugation components are vital to conjugate anabolic efficacy. A combined therapy using an EP4 selective agonist anabolic agent linked to an inactive ALN is presented here that produces significant anabolic effects, allows bone remodeling, and has the potential for treating postmenopausal osteoporosis or other diseases where bone strengthening would be beneficial. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Resveratrol derivative-rich melinjo seed extract induces healing in a murine model of established periodontitis.

BACKGROUND: Products of internal defense systems, like pro-inflammatory cytokines, reactive oxygen species, and leukocytes, are released which attack periodontal bacteria in periodontitis, but at the same time, lead to tissue destruction as well. We hypothesize that resveratrol derivative-rich melinjo seed extract (MSE), an edible plant extract that has antioxidant properties, should promote healing of periodontal bone loss and modulating immune-inflammatory systems that leads periodontal tissue destruction. METHODS: We used an experimentally induced periodontitis (EP) model in mice. Ligatures were placed first for development of EP (15 days). MSE was intraperitoneally administrated (0.001% (w/w)) to reverse bone loss that had already occurred in established EP and mice were then sacrificed (day 17, 20 and 22). RESULTS: Morphometric outcomes revealed lower bone-loss in the MSE groups compared to control. Immunohistochemistry assays demonstrated lower oxidative stress in MSE groups. MSE also inhibited M-CSF/sRANKL mediated osteoclast formation and down-regulated osteoclast activity. CONCLUSIONS: Treatment with MSE in EP actually caused healing of bone, and these effects are probably related to decreases in local oxidative damage and osteoclast activity. Given MSE's positive effects on osteodifferentiation as well, these findings suggest that MSE could be a useful therapeutic agent for the management of periodontitis.

Targeting the isoprenoid pathway to abrogate progression of pulmonary fibrosis.

Fibrotic remodeling in lung injury is a major cause of morbidity. The mechanism that mediates the ongoing fibrosis is unclear, and there is no available treatment to abate the aberrant repair. Reactive oxygen species (ROS) have a critical role in inducing fibrosis by modulating extracellular matrix deposition. Specifically, mitochondrial hydrogen peroxide (H2O2) production by alveolar macrophages is directly linked to pulmonary fibrosis as inhibition of mitochondrial H2O2 attenuates the fibrotic response in mice. Prior studies indicate that the small GTP-binding protein, Rac1, directly mediates H2O2 generation in the mitochondrial intermembrane space. Geranylgeranylation of the C-terminal cysteine residue (Cys(189)) is required for Rac1 activation and mitochondrial import. We hypothesized that impairment of geranylgeranylation would limit mitochondrial oxidative stress and, thus, abrogate progression of pulmonary fibrosis. By targeting the isoprenoid pathway with a novel agent, digeranyl bisphosphonate (DGBP), which impairs geranylgeranylation, we demonstrate that Rac1 mitochondrial import, mitochondrial oxidative stress, and progression of the fibrotic response to lung injury are significantly attenuated. These observations reveal that targeting the isoprenoid pathway to alter Rac1 geranylgeranylation halts the progression of pulmonary fibrosis after lung injury.

The phosphatidylserine receptor TIM4 utilizes integrins as coreceptors to effect phagocytosis.

T-cell immunoglobulin mucin protein 4 (TIM4), a phosphatidylserine (PtdSer)-binding receptor, mediates the phagocytosis of apoptotic cells. How TIM4 exerts its function is unclear, and conflicting data have emerged. To define the mode of action of TIM4, we used two distinct but complementary approaches: 1) we compared bone marrow-derived macrophages from wild-type and TIM4(-/-) mice, and 2) we heterologously expressed TIM4 in epithelioid AD293 cells, which rendered them competent for engulfment of PtdSer-bearing targets. Using these systems, we demonstrate that rather than serving merely as a tether, as proposed earlier by others, TIM4 is an active participant in the phagocytic process. Furthermore, we find that TIM4 operates independently of lactadherin, which had been proposed to act as a bridging molecule. Of interest, TIM4-driven phagocytosis depends on the activation of integrins and involves stimulation of Src-family kinases and focal adhesion kinase, as well as the localized accumulation of phosphatidylinositol 3,4,5-trisphosphate. These mediators promote recruitment of the nucleotide-exchange factor Vav3, which in turn activates small Rho-family GTPases. Gene silencing or ablation experiments demonstrated that RhoA, Rac1, and Rac2 act synergistically to drive the remodeling of actin that underlies phagocytosis. Single-particle detection experiments demonstrated that TIM4 and ß1 integrins associate upon receptor clustering. These findings support a model in which TIM4 engages integrins as coreceptors to evoke the signal transduction needed to internalize PtdSer-bearing targets such as apoptotic cells.

The impact of integration of dental services on oral health in long-term care: qualitative analysis.

OBJECTIVES: To qualitatively analyse how integration of dental service in long-term care (LTC) impacts residents and their oral health. BACKGROUND: Few studies have attempted to merge inductive and deductive data to clarify the significance of the complex psychosocial environment in LTC facilities. Understanding the subjective oral health experience of LTC residents in their social setting is key to uncovering behavioural patterns that may be limiting the oral care provided to LTC residents. MATERIALS AND METHODS: A cross-sectional study was performed involving 61 residents in three Ontario LTC facilities. Observations and reflective notes were recorded during open-ended interviews using a structured questionnaire to stimulate conversation topics. This ensured that each resident received the same prompting during the interview process. Inductive analysis was used to identify common patterns and themes within field notes and transcriptions. RESULTS: The major themes identified included oral hygiene, oral discomfort, general health, appearance, dental access, and denture related issues. Oral hygiene and discomfort were the dominating categories within the facilities. CONCLUSION: Two of the three LTC centres identified in this study failed to provide appropriate oral care for their residents. Future research needs to be directed at prospective studies assessing the effect of oral health education and mandatory dental examinations o entry within LTC centres utilising qualitative and quantitative analyses.